Imposed hyperthermia has been used to destroy tumors in human patients as well as in experimental animals. Yet the process of tumor regression induced by hyperthermia is not understood. The objectives of the project are: 1) To measure the glucose transport across the membrane as a function of "heat dose" using the tracer technique and the light beating spectroscopy. To measure the temperature coefficient (Q10), the kinetics of the uptake, and Km for the transport. 2) To measure the fluorescence intensity change to monitor the membrane potential change after different amounts of "heat dose". 3) To measure the translational diffusion constant of pyrene using its eximer decay curves. The membrane viscosity can be obtained from the decay curve. This study will answer whether the fluorescence probes can be used to monitor the tumor regression. It will also answer whether the membrane potential and fluidity suffer irreversible damages after a certain period of heat exposure, and whether, if such damages occur, they are the causes of changes in glucose uptake. Finally, one may answer whether there is a correlation in the changes of the membrane fluidity and the membrane potential.